1. Field of the Invention
The invention relates to the field of vibration isolation and more particularly to vibration damping and isolation for devices having extremely low vibration specifications.
2. Description of the Prior Art
Reaction wheel assemblies on pointing control systems are crucial elements of a telescopic system. These assemblies, however, significantly contribute vibration components to the system during operation. Since telescopes have stringent pointing requirements there is a need to isolate the vibration induced by the reaction wheel, most significantly of which are caused by the axial forces attributable to the bearing of the ball on the inner and outer races and imperfections in the ball itself.
One prior art solution to the problem, known as a wire rope, utilizes several stranded wires wrapped in a circle and attached at one end to a base or ground and at the other end to the device or payload to be isolatd. Compliance and isolation are provided by the flexibility of the wire and Coulomb damping or energy absorption is provided by the wires rubbing together. This device has several short comings which include, low damping and stiffness characteristics which are variable with the magnitude of the input vibration level, performance changes with environmental variations, and mathematical complexities that require an iteration procedure of design and test before reaching a final configuration.
A second solution of the prior art utilizes viscoelastic materials as the isolating element. These devices though capable of providing isolation for most applications, exhibit excessive sensitivity to temperature and other environmental conditions.